August 19, 2019

Cold Crashing Beer for Crystal Clear Homebrew

It’s the time of year where many brewers are planning crisp and refreshing brews to tackle the summer heat. And while everyone has their favorite styles, most folks equate crisp and refreshing with light-colored and crystal clear pints of beer.

Clarity is not a priority for every brewer or brew, and many beers will turn out fairly clear without any help. But those lawnmower beers don’t look quite as refreshing if they’re hazy. Even without kegging systems or filtering equipment, there are some techniques that can help. One of those is cold crashing.

Cold crashing is performed when the beer is fully fermented and ready to be packaged. The process involves lowering the temperature of the beer very quickly to near-freezing and holding it for about 24 hours. You can achieve this using a temperature controller.

Once the beer has cleared, it is packaged. This process does require a fridge large enough to hold your fermenter or some other method of rapid cooling.

The goal is to force the remaining beer yeast to flocculate (clump together and fall out of suspension). This can be especially helpful when using a strain with low to medium flocculation performance during fermentation.

When cold crashing a fermenter, the change in temperature may cause air to be pulled in through the airlock. This is not a reason to worry as there should still be more than enough CO2 blanketing the beer to prevent oxidation...as long as you do not shake it up too much moving it around.

If you keg your beer, you can cold crash right in a keg. This allows you to purge the keg with CO2 and not even worry about oxygen getting in. Let the keg condition (uncarbonated) for a few days in your kegerator and the remaining yeast will drop out. If you want a very clear and stable beer, you can even push the beer to a second keg (using a keg jumper and CO2 pressure) leaving all the sediment behind.

If bottle conditioning, do not be concerned about having too much yeast fall out of suspension. There are plenty of cells left to carbonate your beer. Keep in mind, it may take longer than normal, depending on the yeast strain and the beer. Just give it time. If you need a quick turn around, you can always add dry yeast during the bottling process. Lallemand CBC-1 is designed for bottle conditioning. After cold crashing, bottle your beer and let the bottles carbonate at room temperature like normal.

As a side effect, cold crashing will actually promote the occurrence of chill haze. While chill haze is best prevented earlier in the brewing process (perhaps a topic for another article), if it forms during the cold crashing stage, the use of gelatin finings will help clear that up before packaging.